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New geometric datum progress and plans. joe.evjen@noaa.gov. 2011 US Topo Map. Slide by John Kosovich, USGS. Simplified Concept of NAD 83 vs. ITRF2008. h 08. h 83. Earth’s. Surface. ITRF2008. Origin. 2.2 meters. NAD 83. Origin. NAD 83(2011) to IGS08 at epoch 2022.0.
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New geometric datumprogress and plans joe.evjen@noaa.gov
2011 US Topo Map Slide by John Kosovich, USGS
Simplified Concept of NAD 83 vs. ITRF2008 h08 h83 Earth’s Surface ITRF2008 Origin 2.2 meters NAD 83 Origin
Measures of Success • FGDC votes to adopt the new datum for U.S. geospatial data. • All NOAA geospatial products are consistent with the new datum. • NOAA geospatial products are understood and accepted by users. • Tools exist which facilitate modernization of legacy data. • New datums replace NAD83/NAVD88 in state and local regulations, documentation Risks • “Existing datums are good enough”, reduces enthusiasm for adopting the new. • Access to global (ITRF) & local (RTN, LDP) frames reduces the utility of a NAREF frame. • Das Unheimliche; frustration and cognitive dissonance increase with accuracy. Assumptions • IERS will continue to provide an ITRF common to all GNSS & other navigation systems. • GIS vendors will provide user-friendly solutions to modernize legacy data.
Source: Zurich-American Insurance Group A man with one watch will always know the time, A man with two watches will always be in doubt. • accessible • accurate • constant • seamless • simple
metadata to the rescue • your positional metadata should include: • datum • epoch • source • these will facilitate transforming from current to new datum • maintaining your original survey data will provide more accurate results
eppur si muove <and yet it moves> • A fixed reference frame will drift from international frame, at different rates for “unstable” parts of US
U.S. CORS Velocity Field – ITRF2008 (IGS08 epoch 2005.0) • accessible • accurate • constant • seamless • simple
U.S. CORS Velocity Field - NAD83(2011) epoch 2010.0 • accessible • accurate • constant • seamless • simple